1. Technical Field
The present invention relates to image sensor package structures. More particularly, the present invention relates to an image sensor package structure with a large air cavity, wherein the image sensor package structure provides an improved image-sensing effect.
2. Description of Related Art
With the ongoing progress of technology, all manufacturers of electronic multimedia devices have made every effort to improve functionality and performance of their products with the attempt to meet all the consumer demands related to audio and/or video entertainments. In such popular electronic multimedia devices, image sensors play a critical role. An image sensor serves to receive and convert optical signals into electrical signals, and transmit the electrical signals to an external device that analyzes the electrical signals. When incorporated in an electronic device, the image sensor enables the electronic device to take still and/or dynamic images.
A conventional image sensor package is mainly constructed by placing an image sensor chip on a substrate, and electrically connecting the two with metal conducting wires, so that a signal connection between the image sensor chip and the substrate can be established. Next, a transparent lid (e.g. glass), which allows light to pass through and be captured by the image sensor chip, is settled above the image sensor chip, thereby completing the package structure. Such an image sensor package structure may be later integrated with an external device, such as a PCB, to be used in various electronic products such as a DSC (Digital Still Camera), a DV (Digital Video), a security monitoring system, a mobile phone, and a vehicle image sensing module.
In addition to the adaptability to mass manufacturing, another important factor to evaluate an image sensor is its image-sensing performance. Traditionally in downsizing an image sensor, it is the general approach to adhere the transparent lid right on top of the image sensor chip, resulting in a very short distance between the transparent lid and the image sensor chip. As a result, when light passes through the transparent lid and enters into the sensitization area of the image sensor chip, the multi-refraction or multi-reflection of light is likely to occur, leading to poor imaging quality as well as ghost images.